blockstorage.cpp

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// Copyright (c) 2011-2022 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <node/blockstorage.h>
 
#include <blockindexcomparators.h>
#include <chain.h>
#include <chainparams.h>
#include <clientversion.h>
#include <config.h>
#include <consensus/validation.h>
#include <flatfile.h>
#include <fs.h>
#include <hash.h>
#include <pow/pow.h>
#include <reverse_iterator.h>
#include <shutdown.h>
#include <streams.h>
#include <undo.h>
#include <util/system.h>
#include <validation.h>
 
#include <map>
 
namespace node {
std::atomic_bool fReindex(false);
 
static FILE *OpenUndoFile(const FlatFilePos &pos, bool fReadOnly = false);
 
static FlatFileSeq BlockFileSeq();
static FlatFileSeq UndoFileSeq();
 
std::vector<CBlockIndex *> BlockManager::GetAllBlockIndices() {
    AssertLockHeld(cs_main);
    std::vector<CBlockIndex *> rv;
    rv.reserve(m_block_index.size());
    for (auto &[_, block_index] : m_block_index) {
        rv.push_back(&block_index);
    }
    return rv;
}
 
CBlockIndex *BlockManager::LookupBlockIndex(const BlockHash &hash) {
    AssertLockHeld(cs_main);
    BlockMap::iterator it = m_block_index.find(hash);
    return it == m_block_index.end() ? nullptr : &it->second;
}
 
const CBlockIndex *BlockManager::LookupBlockIndex(const BlockHash &hash) const {
    AssertLockHeld(cs_main);
    BlockMap::const_iterator it = m_block_index.find(hash);
    return it == m_block_index.end() ? nullptr : &it->second;
}
 
CBlockIndex *BlockManager::AddToBlockIndex(const CBlockHeader &block,
                                           CBlockIndex *&best_header) {
    AssertLockHeld(cs_main);
 
    const auto [mi, inserted] =
        m_block_index.try_emplace(block.GetHash(), block);
    if (!inserted) {
        return &mi->second;
    }
    CBlockIndex *pindexNew = &(*mi).second;
 
    // We assign the sequence id to blocks only when the full data is available,
    // to avoid miners withholding blocks but broadcasting headers, to get a
    // competitive advantage.
    pindexNew->nSequenceId = 0;
 
    pindexNew->phashBlock = &((*mi).first);
    BlockMap::iterator miPrev = m_block_index.find(block.hashPrevBlock);
    if (miPrev != m_block_index.end()) {
        pindexNew->pprev = &(*miPrev).second;
        pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
        pindexNew->BuildSkip();
    }
    pindexNew->nTimeReceived = GetTime();
    pindexNew->nTimeMax =
        (pindexNew->pprev
             ? std::max(pindexNew->pprev->nTimeMax, pindexNew->nTime)
             : pindexNew->nTime);
    pindexNew->nChainWork =
        (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) +
        GetBlockProof(*pindexNew);
    pindexNew->RaiseValidity(BlockValidity::TREE);
    if (best_header == nullptr ||
        best_header->nChainWork < pindexNew->nChainWork) {
        best_header = pindexNew;
    }
 
    m_dirty_blockindex.insert(pindexNew);
    return pindexNew;
}
 
void BlockManager::PruneOneBlockFile(const int fileNumber) {
    AssertLockHeld(cs_main);
    LOCK(cs_LastBlockFile);
 
    for (auto &entry : m_block_index) {
        CBlockIndex *pindex = &entry.second;
        if (pindex->nFile == fileNumber) {
            pindex->nStatus = pindex->nStatus.withData(false).withUndo(false);
            pindex->nFile = 0;
            pindex->nDataPos = 0;
            pindex->nUndoPos = 0;
            m_dirty_blockindex.insert(pindex);
 
            // Prune from m_blocks_unlinked -- any block we prune would have
            // to be downloaded again in order to consider its chain, at which
            // point it would be considered as a candidate for
            // m_blocks_unlinked or setBlockIndexCandidates.
            auto range = m_blocks_unlinked.equal_range(pindex->pprev);
            while (range.first != range.second) {
                std::multimap<CBlockIndex *, CBlockIndex *>::iterator _it =
                    range.first;
                range.first++;
                if (_it->second == pindex) {
                    m_blocks_unlinked.erase(_it);
                }
            }
        }
    }
 
    m_blockfile_info[fileNumber].SetNull();
    m_dirty_fileinfo.insert(fileNumber);
}
 
void BlockManager::FindFilesToPruneManual(std::set<int> &setFilesToPrune,
                                          int nManualPruneHeight,
                                          int chain_tip_height) {
    assert(IsPruneMode() && nManualPruneHeight > 0);
 
    LOCK2(cs_main, cs_LastBlockFile);
    if (chain_tip_height < 0) {
        return;
    }
 
    // last block to prune is the lesser of (user-specified height,
    // MIN_BLOCKS_TO_KEEP from the tip)
    unsigned int nLastBlockWeCanPrune{std::min(
        (unsigned)nManualPruneHeight, chain_tip_height - MIN_BLOCKS_TO_KEEP)};
    int count = 0;
    for (int fileNumber = 0; fileNumber < m_last_blockfile; fileNumber++) {
        if (m_blockfile_info[fileNumber].nSize == 0 ||
            m_blockfile_info[fileNumber].nHeightLast > nLastBlockWeCanPrune) {
            continue;
        }
        PruneOneBlockFile(fileNumber);
        setFilesToPrune.insert(fileNumber);
        count++;
    }
    LogPrintf("Prune (Manual): prune_height=%d removed %d blk/rev pairs\n",
              nLastBlockWeCanPrune, count);
}
 
void BlockManager::FindFilesToPrune(std::set<int> &setFilesToPrune,
                                    uint64_t nPruneAfterHeight,
                                    int chain_tip_height, int prune_height,
                                    bool is_ibd) {
    LOCK2(cs_main, cs_LastBlockFile);
    if (chain_tip_height < 0 || GetPruneTarget() == 0) {
        return;
    }
    if (uint64_t(chain_tip_height) <= nPruneAfterHeight) {
        return;
    }
 
    unsigned int nLastBlockWeCanPrune = std::min(
        prune_height, chain_tip_height - static_cast<int>(MIN_BLOCKS_TO_KEEP));
    uint64_t nCurrentUsage = CalculateCurrentUsage();
    // We don't check to prune until after we've allocated new space for files,
    // so we should leave a buffer under our target to account for another
    // allocation before the next pruning.
    uint64_t nBuffer = BLOCKFILE_CHUNK_SIZE + UNDOFILE_CHUNK_SIZE;
    uint64_t nBytesToPrune;
    int count = 0;
 
    if (nCurrentUsage + nBuffer >= GetPruneTarget()) {
        // On a prune event, the chainstate DB is flushed.
        // To avoid excessive prune events negating the benefit of high dbcache
        // values, we should not prune too rapidly.
        // So when pruning in IBD, increase the buffer a bit to avoid a re-prune
        // too soon.
        if (is_ibd) {
            // Since this is only relevant during IBD, we use a fixed 10%
            nBuffer += GetPruneTarget() / 10;
        }
 
        for (int fileNumber = 0; fileNumber < m_last_blockfile; fileNumber++) {
            nBytesToPrune = m_blockfile_info[fileNumber].nSize +
                            m_blockfile_info[fileNumber].nUndoSize;
 
            if (m_blockfile_info[fileNumber].nSize == 0) {
                continue;
            }
 
            // are we below our target?
            if (nCurrentUsage + nBuffer < GetPruneTarget()) {
                break;
            }
 
            // don't prune files that could have a block within
            // MIN_BLOCKS_TO_KEEP of the main chain's tip but keep scanning
            if (m_blockfile_info[fileNumber].nHeightLast >
                nLastBlockWeCanPrune) {
                continue;
            }
 
            PruneOneBlockFile(fileNumber);
            // Queue up the files for removal
            setFilesToPrune.insert(fileNumber);
            nCurrentUsage -= nBytesToPrune;
            count++;
        }
    }
 
    LogPrint(BCLog::PRUNE,
             "Prune: target=%dMiB actual=%dMiB diff=%dMiB "
             "max_prune_height=%d removed %d blk/rev pairs\n",
             GetPruneTarget() / 1024 / 1024, nCurrentUsage / 1024 / 1024,
             (int64_t(GetPruneTarget()) - int64_t(nCurrentUsage)) / 1024 / 1024,
             nLastBlockWeCanPrune, count);
}
 
CBlockIndex *BlockManager::InsertBlockIndex(const BlockHash &hash) {
    AssertLockHeld(cs_main);
 
    if (hash.IsNull()) {
        return nullptr;
    }
 
    const auto [mi, inserted] = m_block_index.try_emplace(hash);
    CBlockIndex *pindex = &(*mi).second;
    if (inserted) {
        pindex->phashBlock = &((*mi).first);
    }
    return pindex;
}
 
bool BlockManager::LoadBlockIndex() {
    AssertLockHeld(cs_main);
    if (!m_block_tree_db->LoadBlockIndexGuts(
            GetConsensus(),
            [this](const BlockHash &hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
                return this->InsertBlockIndex(hash);
            })) {
        return false;
    }
 
    // Calculate nChainWork
    std::vector<CBlockIndex *> vSortedByHeight{GetAllBlockIndices()};
    std::sort(vSortedByHeight.begin(), vSortedByHeight.end(),
              CBlockIndexHeightOnlyComparator());
 
    for (CBlockIndex *pindex : vSortedByHeight) {
        if (ShutdownRequested()) {
            return false;
        }
        pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) +
                             GetBlockProof(*pindex);
        pindex->nTimeMax =
            (pindex->pprev ? std::max(pindex->pprev->nTimeMax, pindex->nTime)
                           : pindex->nTime);
 
        // We can link the chain of blocks for which we've received
        // transactions at some point, or blocks that are assumed-valid on the
        // basis of snapshot load (see PopulateAndValidateSnapshot()).
        // Pruned nodes may have deleted the block.
        if (pindex->nTx > 0) {
            if (!pindex->UpdateChainStats() && pindex->pprev) {
                m_blocks_unlinked.insert(std::make_pair(pindex->pprev, pindex));
            }
        }
 
        if (!pindex->nStatus.hasFailed() && pindex->pprev &&
            pindex->pprev->nStatus.hasFailed()) {
            pindex->nStatus = pindex->nStatus.withFailedParent();
            m_dirty_blockindex.insert(pindex);
        }
 
        if (pindex->pprev) {
            pindex->BuildSkip();
        }
    }
 
    return true;
}
 
bool BlockManager::WriteBlockIndexDB() {
    std::vector<std::pair<int, const CBlockFileInfo *>> vFiles;
    vFiles.reserve(m_dirty_fileinfo.size());
    for (int i : m_dirty_fileinfo) {
        vFiles.push_back(std::make_pair(i, &m_blockfile_info[i]));
    }
 
    m_dirty_fileinfo.clear();
 
    std::vector<const CBlockIndex *> vBlocks;
    vBlocks.reserve(m_dirty_blockindex.size());
    for (const CBlockIndex *cbi : m_dirty_blockindex) {
        vBlocks.push_back(cbi);
    }
 
    m_dirty_blockindex.clear();
 
    if (!m_block_tree_db->WriteBatchSync(vFiles, m_last_blockfile, vBlocks)) {
        return false;
    }
    return true;
}
 
bool BlockManager::LoadBlockIndexDB() {
    if (!LoadBlockIndex()) {
        return false;
    }
 
    // Load block file info
    m_block_tree_db->ReadLastBlockFile(m_last_blockfile);
    m_blockfile_info.resize(m_last_blockfile + 1);
    LogPrintf("%s: last block file = %i\n", __func__, m_last_blockfile);
    for (int nFile = 0; nFile <= m_last_blockfile; nFile++) {
        m_block_tree_db->ReadBlockFileInfo(nFile, m_blockfile_info[nFile]);
    }
    LogPrintf("%s: last block file info: %s\n", __func__,
              m_blockfile_info[m_last_blockfile].ToString());
    for (int nFile = m_last_blockfile + 1; true; nFile++) {
        CBlockFileInfo info;
        if (m_block_tree_db->ReadBlockFileInfo(nFile, info)) {
            m_blockfile_info.push_back(info);
        } else {
            break;
        }
    }
 
    // Check presence of blk files
    LogPrintf("Checking all blk files are present...\n");
    std::set<int> setBlkDataFiles;
    for (const auto &[_, block_index] : m_block_index) {
        if (block_index.nStatus.hasData()) {
            setBlkDataFiles.insert(block_index.nFile);
        }
    }
 
    for (const int i : setBlkDataFiles) {
        FlatFilePos pos(i, 0);
        if (CAutoFile(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION)
                .IsNull()) {
            return false;
        }
    }
 
    // Check whether we have ever pruned block & undo files
    m_block_tree_db->ReadFlag("prunedblockfiles", m_have_pruned);
    if (m_have_pruned) {
        LogPrintf(
            "LoadBlockIndexDB(): Block files have previously been pruned\n");
    }
 
    // Check whether we need to continue reindexing
    if (m_block_tree_db->IsReindexing()) {
        fReindex = true;
    }
 
    return true;
}
 
const CBlockIndex *
BlockManager::GetLastCheckpoint(const CCheckpointData &data) {
    const MapCheckpoints &checkpoints = data.mapCheckpoints;
 
    for (const MapCheckpoints::value_type &i : reverse_iterate(checkpoints)) {
        const BlockHash &hash = i.second;
        const CBlockIndex *pindex = LookupBlockIndex(hash);
        if (pindex) {
            return pindex;
        }
    }
 
    return nullptr;
}
 
bool BlockManager::IsBlockPruned(const CBlockIndex *pblockindex) {
    AssertLockHeld(::cs_main);
    return (m_have_pruned && !pblockindex->nStatus.hasData() &&
            pblockindex->nTx > 0);
}
 
const CBlockIndex *GetFirstStoredBlock(const CBlockIndex *start_block) {
    AssertLockHeld(::cs_main);
    assert(start_block);
    const CBlockIndex *last_block = start_block;
    while (last_block->pprev && (last_block->pprev->nStatus.hasData())) {
        last_block = last_block->pprev;
    }
    return last_block;
}
 
// If we're using -prune with -reindex, then delete block files that will be
// ignored by the reindex.  Since reindexing works by starting at block file 0
// and looping until a blockfile is missing, do the same here to delete any
// later block files after a gap. Also delete all rev files since they'll be
// rewritten by the reindex anyway. This ensures that m_blockfile_info is in
// sync with what's actually on disk by the time we start downloading, so that
// pruning works correctly.
void CleanupBlockRevFiles() {
    std::map<std::string, fs::path> mapBlockFiles;
 
    // Glob all blk?????.dat and rev?????.dat files from the blocks directory.
    // Remove the rev files immediately and insert the blk file paths into an
    // ordered map keyed by block file index.
    LogPrintf("Removing unusable blk?????.dat and rev?????.dat files for "
              "-reindex with -prune\n");
    for (const auto &file : fs::directory_iterator{gArgs.GetBlocksDirPath()}) {
        const std::string path = fs::PathToString(file.path().filename());
        if (fs::is_regular_file(file) && path.length() == 12 &&
            path.substr(8, 4) == ".dat") {
            if (path.substr(0, 3) == "blk") {
                mapBlockFiles[path.substr(3, 5)] = file.path();
            } else if (path.substr(0, 3) == "rev") {
                remove(file.path());
            }
        }
    }
 
    // Remove all block files that aren't part of a contiguous set starting at
    // zero by walking the ordered map (keys are block file indices) by keeping
    // a separate counter. Once we hit a gap (or if 0 doesn't exist) start
    // removing block files.
    int contiguousCounter = 0;
    for (const auto &item : mapBlockFiles) {
        if (atoi(item.first) == contiguousCounter) {
            contiguousCounter++;
            continue;
        }
        remove(item.second);
    }
}
 
CBlockFileInfo *BlockManager::GetBlockFileInfo(size_t n) {
    LOCK(cs_LastBlockFile);
 
    return &m_blockfile_info.at(n);
}
 
static bool UndoWriteToDisk(const CBlockUndo &blockundo, FlatFilePos &pos,
                            const BlockHash &hashBlock,
                            const CMessageHeader::MessageMagic &messageStart) {
    // Open history file to append
    CAutoFile fileout(OpenUndoFile(pos), SER_DISK, CLIENT_VERSION);
    if (fileout.IsNull()) {
        return error("%s: OpenUndoFile failed", __func__);
    }
 
    // Write index header
    unsigned int nSize = GetSerializeSize(blockundo, fileout.GetVersion());
    fileout << messageStart << nSize;
 
    // Write undo data
    long fileOutPos = ftell(fileout.Get());
    if (fileOutPos < 0) {
        return error("%s: ftell failed", __func__);
    }
    pos.nPos = (unsigned int)fileOutPos;
    fileout << blockundo;
 
    // calculate & write checksum
    CHashWriter hasher(SER_GETHASH, PROTOCOL_VERSION);
    hasher << hashBlock;
    hasher << blockundo;
    fileout << hasher.GetHash();
 
    return true;
}
 
bool UndoReadFromDisk(CBlockUndo &blockundo, const CBlockIndex *pindex) {
    const FlatFilePos pos{WITH_LOCK(::cs_main, return pindex->GetUndoPos())};
 
    if (pos.IsNull()) {
        return error("%s: no undo data available", __func__);
    }
 
    // Open history file to read
    CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
    if (filein.IsNull()) {
        return error("%s: OpenUndoFile failed", __func__);
    }
 
    // Read block
    uint256 hashChecksum;
    // We need a CHashVerifier as reserializing may lose data
    CHashVerifier<CAutoFile> verifier(&filein);
    try {
        verifier << pindex->pprev->GetBlockHash();
        verifier >> blockundo;
        filein >> hashChecksum;
    } catch (const std::exception &e) {
        return error("%s: Deserialize or I/O error - %s", __func__, e.what());
    }
 
    // Verify checksum
    if (hashChecksum != verifier.GetHash()) {
        return error("%s: Checksum mismatch", __func__);
    }
 
    return true;
}
 
void BlockManager::FlushUndoFile(int block_file, bool finalize) {
    FlatFilePos undo_pos_old(block_file,
                             m_blockfile_info[block_file].nUndoSize);
    if (!UndoFileSeq().Flush(undo_pos_old, finalize)) {
        AbortNode("Flushing undo file to disk failed. This is likely the "
                  "result of an I/O error.");
    }
}
 
void BlockManager::FlushBlockFile(bool fFinalize, bool finalize_undo) {
    LOCK(cs_LastBlockFile);
 
    if (m_blockfile_info.empty()) {
        // Return if we haven't loaded any blockfiles yet. This happens during
        // chainstate init, when we call
        // ChainstateManager::MaybeRebalanceCaches() (which then calls
        // FlushStateToDisk()), resulting in a call to this function before we
        // have populated `m_blockfile_info` via LoadBlockIndexDB().
        return;
    }
    assert(static_cast<int>(m_blockfile_info.size()) > m_last_blockfile);
 
    FlatFilePos block_pos_old(m_last_blockfile,
                              m_blockfile_info[m_last_blockfile].nSize);
    if (!BlockFileSeq().Flush(block_pos_old, fFinalize)) {
        AbortNode("Flushing block file to disk failed. This is likely the "
                  "result of an I/O error.");
    }
    // we do not always flush the undo file, as the chain tip may be lagging
    // behind the incoming blocks,
    // e.g. during IBD or a sync after a node going offline
    if (!fFinalize || finalize_undo) {
        FlushUndoFile(m_last_blockfile, finalize_undo);
    }
}
 
uint64_t BlockManager::CalculateCurrentUsage() {
    LOCK(cs_LastBlockFile);
 
    uint64_t retval = 0;
    for (const CBlockFileInfo &file : m_blockfile_info) {
        retval += file.nSize + file.nUndoSize;
    }
 
    return retval;
}
 
void UnlinkPrunedFiles(const std::set<int> &setFilesToPrune) {
    for (const int i : setFilesToPrune) {
        FlatFilePos pos(i, 0);
        fs::remove(BlockFileSeq().FileName(pos));
        fs::remove(UndoFileSeq().FileName(pos));
        LogPrint(BCLog::BLOCKSTORE, "Prune: %s deleted blk/rev (%05u)\n",
                 __func__, i);
    }
}
 
static FlatFileSeq BlockFileSeq() {
    return FlatFileSeq(gArgs.GetBlocksDirPath(), "blk",
                       gArgs.GetBoolArg("-fastprune", false)
                           ? 0x4000 /* 16kb */
                           : BLOCKFILE_CHUNK_SIZE);
}
 
static FlatFileSeq UndoFileSeq() {
    return FlatFileSeq(gArgs.GetBlocksDirPath(), "rev", UNDOFILE_CHUNK_SIZE);
}
 
FILE *OpenBlockFile(const FlatFilePos &pos, bool fReadOnly) {
    return BlockFileSeq().Open(pos, fReadOnly);
}
 
static FILE *OpenUndoFile(const FlatFilePos &pos, bool fReadOnly) {
    return UndoFileSeq().Open(pos, fReadOnly);
}
 
fs::path GetBlockPosFilename(const FlatFilePos &pos) {
    return BlockFileSeq().FileName(pos);
}
 
bool BlockManager::FindBlockPos(FlatFilePos &pos, unsigned int nAddSize,
                                unsigned int nHeight, CChain &active_chain,
                                uint64_t nTime, bool fKnown) {
    LOCK(cs_LastBlockFile);
 
    unsigned int nFile = fKnown ? pos.nFile : m_last_blockfile;
    if (m_blockfile_info.size() <= nFile) {
        m_blockfile_info.resize(nFile + 1);
    }
 
    bool finalize_undo = false;
    if (!fKnown) {
        unsigned int max_blockfile_size{MAX_BLOCKFILE_SIZE};
        // Use smaller blockfiles in test-only -fastprune mode - but avoid
        // the possibility of having a block not fit into the block file.
        if (gArgs.GetBoolArg("-fastprune", false)) {
            max_blockfile_size = 0x10000; // 64kiB
            if (nAddSize >= max_blockfile_size) {
                // dynamically adjust the blockfile size to be larger than the
                // added size
                max_blockfile_size = nAddSize + 1;
            }
        }
        // TODO: we will also need to dynamically adjust the blockfile size
        //   or raise MAX_BLOCKFILE_SIZE when we reach block sizes larger than
        //   128 MiB
        assert(nAddSize < max_blockfile_size);
        while (m_blockfile_info[nFile].nSize + nAddSize >= max_blockfile_size) {
            // when the undo file is keeping up with the block file, we want to
            // flush it explicitly when it is lagging behind (more blocks arrive
            // than are being connected), we let the undo block write case
            // handle it
            finalize_undo = (m_blockfile_info[nFile].nHeightLast ==
                             (unsigned int)active_chain.Tip()->nHeight);
            nFile++;
            if (m_blockfile_info.size() <= nFile) {
                m_blockfile_info.resize(nFile + 1);
            }
        }
        pos.nFile = nFile;
        pos.nPos = m_blockfile_info[nFile].nSize;
    }
 
    if ((int)nFile != m_last_blockfile) {
        if (!fKnown) {
            LogPrint(BCLog::BLOCKSTORE, "Leaving block file %i: %s\n",
                     m_last_blockfile,
                     m_blockfile_info[m_last_blockfile].ToString());
        }
        FlushBlockFile(!fKnown, finalize_undo);
        m_last_blockfile = nFile;
    }
 
    m_blockfile_info[nFile].AddBlock(nHeight, nTime);
    if (fKnown) {
        m_blockfile_info[nFile].nSize =
            std::max(pos.nPos + nAddSize, m_blockfile_info[nFile].nSize);
    } else {
        m_blockfile_info[nFile].nSize += nAddSize;
    }
 
    if (!fKnown) {
        bool out_of_space;
        size_t bytes_allocated =
            BlockFileSeq().Allocate(pos, nAddSize, out_of_space);
        if (out_of_space) {
            return AbortNode("Disk space is too low!",
                             _("Disk space is too low!"));
        }
        if (bytes_allocated != 0 && IsPruneMode()) {
            m_check_for_pruning = true;
        }
    }
 
    m_dirty_fileinfo.insert(nFile);
    return true;
}
 
bool BlockManager::FindUndoPos(BlockValidationState &state, int nFile,
                               FlatFilePos &pos, unsigned int nAddSize) {
    pos.nFile = nFile;
 
    LOCK(cs_LastBlockFile);
 
    pos.nPos = m_blockfile_info[nFile].nUndoSize;
    m_blockfile_info[nFile].nUndoSize += nAddSize;
    m_dirty_fileinfo.insert(nFile);
 
    bool out_of_space;
    size_t bytes_allocated =
        UndoFileSeq().Allocate(pos, nAddSize, out_of_space);
    if (out_of_space) {
        return AbortNode(state, "Disk space is too low!",
                         _("Disk space is too low!"));
    }
    if (bytes_allocated != 0 && IsPruneMode()) {
        m_check_for_pruning = true;
    }
 
    return true;
}
 
static bool WriteBlockToDisk(const CBlock &block, FlatFilePos &pos,
                             const CMessageHeader::MessageMagic &messageStart) {
    // Open history file to append
    CAutoFile fileout(OpenBlockFile(pos), SER_DISK, CLIENT_VERSION);
    if (fileout.IsNull()) {
        return error("WriteBlockToDisk: OpenBlockFile failed");
    }
 
    // Write index header
    unsigned int nSize = GetSerializeSize(block, fileout.GetVersion());
    fileout << messageStart << nSize;
 
    // Write block
    long fileOutPos = ftell(fileout.Get());
    if (fileOutPos < 0) {
        return error("WriteBlockToDisk: ftell failed");
    }
 
    pos.nPos = (unsigned int)fileOutPos;
    fileout << block;
 
    return true;
}
 
bool BlockManager::WriteUndoDataForBlock(const CBlockUndo &blockundo,
                                         BlockValidationState &state,
                                         CBlockIndex &block) {
    AssertLockHeld(::cs_main);
    // Write undo information to disk
    if (block.GetUndoPos().IsNull()) {
        FlatFilePos _pos;
        if (!FindUndoPos(state, block.nFile, _pos,
                         ::GetSerializeSize(blockundo, CLIENT_VERSION) + 40)) {
            return error("ConnectBlock(): FindUndoPos failed");
        }
        if (!UndoWriteToDisk(blockundo, _pos, block.pprev->GetBlockHash(),
                             GetParams().DiskMagic())) {
            return AbortNode(state, "Failed to write undo data");
        }
        // rev files are written in block height order, whereas blk files are
        // written as blocks come in (often out of order) we want to flush the
        // rev (undo) file once we've written the last block, which is indicated
        // by the last height in the block file info as below; note that this
        // does not catch the case where the undo writes are keeping up with the
        // block writes (usually when a synced up node is getting newly mined
        // blocks) -- this case is caught in the FindBlockPos function
        if (_pos.nFile < m_last_blockfile &&
            static_cast<uint32_t>(block.nHeight) ==
                m_blockfile_info[_pos.nFile].nHeightLast) {
            FlushUndoFile(_pos.nFile, true);
        }
 
        // update nUndoPos in block index
        block.nUndoPos = _pos.nPos;
        block.nStatus = block.nStatus.withUndo();
        m_dirty_blockindex.insert(&block);
    }
 
    return true;
}
 
bool ReadBlockFromDisk(CBlock &block, const FlatFilePos &pos,
                       const Consensus::Params &params) {
    block.SetNull();
 
    // Open history file to read
    CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);
    if (filein.IsNull()) {
        return error("ReadBlockFromDisk: OpenBlockFile failed for %s",
                     pos.ToString());
    }
 
    // Read block
    try {
        filein >> block;
    } catch (const std::exception &e) {
        return error("%s: Deserialize or I/O error - %s at %s", __func__,
                     e.what(), pos.ToString());
    }
 
    // Check the header
    if (!CheckProofOfWork(block.GetHash(), block.nBits, params)) {
        return error("ReadBlockFromDisk: Errors in block header at %s",
                     pos.ToString());
    }
 
    return true;
}
 
bool ReadBlockFromDisk(CBlock &block, const CBlockIndex *pindex,
                       const Consensus::Params &params) {
    const FlatFilePos block_pos{
        WITH_LOCK(cs_main, return pindex->GetBlockPos())};
 
    if (!ReadBlockFromDisk(block, block_pos, params)) {
        return false;
    }
 
    if (block.GetHash() != pindex->GetBlockHash()) {
        return error("ReadBlockFromDisk(CBlock&, CBlockIndex*): GetHash() "
                     "doesn't match index for %s at %s",
                     pindex->ToString(), block_pos.ToString());
    }
 
    return true;
}
 
bool ReadTxFromDisk(CMutableTransaction &tx, const FlatFilePos &pos) {
    // Open history file to read
    CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);
    if (filein.IsNull()) {
        return error("ReadTxFromDisk: OpenBlockFile failed for %s",
                     pos.ToString());
    }
 
    // Read tx
    try {
        filein >> tx;
    } catch (const std::exception &e) {
        return error("%s: Deserialize or I/O error - %s at %s", __func__,
                     e.what(), pos.ToString());
    }
 
    return true;
}
 
bool ReadTxUndoFromDisk(CTxUndo &tx_undo, const FlatFilePos &pos) {
    // Open undo file to read
    CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
    if (filein.IsNull()) {
        return error("ReadTxUndoFromDisk: OpenUndoFile failed for %s",
                     pos.ToString());
    }
 
    // Read undo data
    try {
        filein >> tx_undo;
    } catch (const std::exception &e) {
        return error("%s: Deserialize or I/O error - %s at %s", __func__,
                     e.what(), pos.ToString());
    }
 
    return true;
}
 
FlatFilePos BlockManager::SaveBlockToDisk(const CBlock &block, int nHeight,
                                          CChain &active_chain,
                                          const FlatFilePos *dbp) {
    unsigned int nBlockSize = ::GetSerializeSize(block, CLIENT_VERSION);
    FlatFilePos blockPos;
    const auto position_known{dbp != nullptr};
    if (position_known) {
        blockPos = *dbp;
    } else {
        // When known, blockPos.nPos points at the offset of the block data in
        // the blk file. That already accounts for the serialization header
        // present in the file (the 4 magic message start bytes + the 4 length
        // bytes = 8 bytes = BLOCK_SERIALIZATION_HEADER_SIZE). We add
        // BLOCK_SERIALIZATION_HEADER_SIZE only for new blocks since they will
        // have the serialization header added when written to disk.
        nBlockSize +=
            static_cast<unsigned int>(BLOCK_SERIALIZATION_HEADER_SIZE);
    }
    if (!FindBlockPos(blockPos, nBlockSize, nHeight, active_chain,
                      block.GetBlockTime(), position_known)) {
        error("%s: FindBlockPos failed", __func__);
        return FlatFilePos();
    }
    if (!position_known) {
        if (!WriteBlockToDisk(block, blockPos, GetParams().DiskMagic())) {
            AbortNode("Failed to write block");
            return FlatFilePos();
        }
    }
    return blockPos;
}
 
class ImportingNow {
    std::atomic<bool> &m_importing;
 
public:
    ImportingNow(std::atomic<bool> &importing) : m_importing{importing} {
        assert(m_importing == false);
        m_importing = true;
    }
    ~ImportingNow() {
        assert(m_importing == true);
        m_importing = false;
    }
};
 
void ThreadImport(ChainstateManager &chainman,
                  std::vector<fs::path> vImportFiles, const ArgsManager &args,
                  const fs::path &mempool_path) {
    ScheduleBatchPriority();
 
    {
        ImportingNow imp{chainman.m_blockman.m_importing};
 
        // -reindex
        if (fReindex) {
            int nFile = 0;
            // Map of disk positions for blocks with unknown parent (only used
            // for reindex);  parent hash -> child disk position, multiple
            // children can have the same parent.
            std::multimap<BlockHash, FlatFilePos> blocks_with_unknown_parent;
            while (true) {
                FlatFilePos pos(nFile, 0);
                if (!fs::exists(GetBlockPosFilename(pos))) {
                    // No block files left to reindex
                    break;
                }
                FILE *file = OpenBlockFile(pos, true);
                if (!file) {
                    // This error is logged in OpenBlockFile
                    break;
                }
                LogPrintf("Reindexing block file blk%05u.dat...\n",
                          (unsigned int)nFile);
                chainman.ActiveChainstate().LoadExternalBlockFile(
                    file, &pos, &blocks_with_unknown_parent);
                if (ShutdownRequested()) {
                    LogPrintf("Shutdown requested. Exit %s\n", __func__);
                    return;
                }
                nFile++;
            }
            WITH_LOCK(
                ::cs_main,
                chainman.m_blockman.m_block_tree_db->WriteReindexing(false));
            fReindex = false;
            LogPrintf("Reindexing finished\n");
            // To avoid ending up in a situation without genesis block, re-try
            // initializing (no-op if reindexing worked):
            chainman.ActiveChainstate().LoadGenesisBlock();
        }
 
        // -loadblock=
        for (const fs::path &path : vImportFiles) {
            FILE *file = fsbridge::fopen(path, "rb");
            if (file) {
                LogPrintf("Importing blocks file %s...\n",
                          fs::PathToString(path));
                chainman.ActiveChainstate().LoadExternalBlockFile(file);
                if (ShutdownRequested()) {
                    LogPrintf("Shutdown requested. Exit %s\n", __func__);
                    return;
                }
            } else {
                LogPrintf("Warning: Could not open blocks file %s\n",
                          fs::PathToString(path));
            }
        }
 
        // Reconsider blocks we know are valid. They may have been marked
        // invalid by, for instance, running an outdated version of the node
        // software.
        const MapCheckpoints &checkpoints =
            chainman.GetParams().Checkpoints().mapCheckpoints;
        for (const MapCheckpoints::value_type &i : checkpoints) {
            const BlockHash &hash = i.second;
 
            LOCK(cs_main);
            CBlockIndex *pblockindex =
                chainman.m_blockman.LookupBlockIndex(hash);
            if (pblockindex && !pblockindex->nStatus.isValid()) {
                LogPrintf("Reconsidering checkpointed block %s ...\n",
                          hash.GetHex());
                chainman.ActiveChainstate().ResetBlockFailureFlags(pblockindex);
            }
 
            if (pblockindex && pblockindex->nStatus.isOnParkedChain()) {
                LogPrintf("Unparking checkpointed block %s ...\n",
                          hash.GetHex());
                chainman.ActiveChainstate().UnparkBlockAndChildren(pblockindex);
            }
        }
 
        // scan for better chains in the block chain database, that are not yet
        // connected in the active best chain
 
        // We can't hold cs_main during ActivateBestChain even though we're
        // accessing the chainman unique_ptrs since ABC requires us not to be
        // holding cs_main, so retrieve the relevant pointers before the ABC
        // call.
        for (Chainstate *chainstate :
             WITH_LOCK(::cs_main, return chainman.GetAll())) {
            BlockValidationState state;
            if (!chainstate->ActivateBestChain(state, nullptr)) {
                LogPrintf("Failed to connect best block (%s)\n",
                          state.ToString());
                StartShutdown();
                return;
            }
        }
 
        if (args.GetBoolArg("-stopafterblockimport",
                            DEFAULT_STOPAFTERBLOCKIMPORT)) {
            LogPrintf("Stopping after block import\n");
            StartShutdown();
            return;
        }
    } // End scope of ImportingNow
    chainman.ActiveChainstate().LoadMempool(mempool_path);
}
} // namespace node